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Published online before print August 14, 2006, 10.1148/radiol.2411050271
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(Radiology 2006;241:228-234.)
© RSNA, 2006

Pediatric Imaging

Hemodynamic Investigation of the Left Renal Vein in Pediatric Varicocele: Doppler US, Venography, and Pressure Measurements1

Woo Sun Kim, MD, Jung-Eun Cheon, MD, In-One Kim, MD, Seung Hyup Kim, MD, Kyung Mo Yeon, MD, Kwang Myung Kim, MD and Hwang Choi, MD

1 From the Department of Radiology, Seoul National University College of Medicine and the Institute of Radiation Medicine, SNUMRC, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea (W.S.K., J.E.C., I.O.K., S.H.K., K.M.Y.); and Department of Urology, Seoul National University College of Medicine, Seoul, Korea (K.M.K., H.C.). From the 2001 RSNA Annual Meeting. Received February 16, 2005; revision requested April 14; revision received May 29; accepted June 27; final version accepted November 7. Address correspondence to J.E.C. (e-mail: cheonje{at}snu.ac.kr).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCE IN KNOWLEDGE
 References
 
Purpose: To evaluate prospectively the hemodynamic state of the left renal vein with Doppler ultrasonography (US) and venography in pediatric patients with varicocele to assess the "nutcracker phenomenon."

Materials and Methods: The institutional review board considered this study ethically sound, and parental informed consent was obtained for all subjects. Doppler US of the left renal vein was performed in 27 consecutive boys with varicocele (age range, 7–15 years; mean, 11.9 years) and in 20 boys without varicocele as control subjects (age range, 7–17 years; mean, 11.4 years). Doppler US was used to evaluate left renal vein diameters and peak velocities in the proximal left renal vein near the renal hilum and in the left renal vein between the aorta and superior mesenteric artery (aortomesenteric portion). The diameter ratios and peak velocity ratios between two sites were obtained. For statistical comparison of results, the t test was used. Left renal venography and renocaval pressure measurement were performed in 13 patients with varicocele. The Fisher exact test was used to evaluate the associations between the nutcracker phenomenon (renocaval pressure gradient ≥3 mm Hg) and the development of collateral veins.

Results: The diameters of the proximal left renal vein and the peak velocities in the aortomesenteric portion of the left renal vein were significantly different between the varicocele group and the control group (P < .001). The diameter ratios (5.7 ± 1.8 [standard deviation]) and peak velocity ratios (5.2 ± 2.6) in patients with varicocele were significantly higher than those in control subjects (3.5 ± 1.0 and 3.1 ± 0.8, respectively) (P < .005). According to findings at left renal venography (n = 13), 10 patients (77%) met the criteria for the nutcracker phenomenon. The nutcracker phenomenon was significantly associated with the development of collateral veins (P = .035).

Conclusion: Doppler US and venography of the left renal vein can show hemodynamic changes of the left renal vein and depict the presence of the nutcracker phenomenon in pediatric varicocele.

© RSNA, 2006


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCE IN KNOWLEDGE
 References
 
Varicocele, defined as the abnormal dilatation and varicosity of the pampiniform plexus, is characterized by retrograde flow in the internal spermatic vein and most commonly occurs on the left side of the scrotum (1,2). Although absent or incompetent valves in the internal spermatic vein and resulting retrograde flow have been considered the principal cause of varicocele, retrograde flow from the left renal vein into the internal spermatic vein caused by the "nutcracker phenomenon" (defined as compression of the left renal vein between the aorta and the superior mesenteric artery) has been implicated in the development of varicocele (3–7).

Although selective left renal venography and the measurement of the pressure gradient between the left renal vein and inferior vena cava is still a standard procedure for the diagnosis of the nutcracker phenomenon, it is an invasive procedure (3–9). Doppler ultrasonography (US) has been used as a noninvasive imaging tool for the diagnosis of the nutcracker phenomenon in adults (10–13). The purpose of our study was to evaluate prospectively the hemodynamic state of the left renal vein with Doppler US and venography in pediatric patients with varicocele to assess the nutcracker phenomenon.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 ADVANCE IN KNOWLEDGE
 References
 
Subjects
Between January 1997 and December 2003, 27 consecutive boys (age range, 7–15 years; mean, 11.9 years) with varicocele were referred to the radiology department for US evaluation of varicocele from an outpatient pediatric urology clinic. All patients had reported scrotal swelling with (n = 11) or without (n = 16) dull pain in the groin area. All patients underwent scrotal US and Doppler spectral analysis of the left renal vein. All patients had clinically palpable varicocele. In our study, varicocele was classified at clinical examination into high and low grades as follows: High-grade varicocele (n = 19) was defined as being visible in an erect position and palpable in a supine position during normal respiration, and low-grade varicocele (n = 8) was defined as being palpable in an erect position during normal respiration or in a supine position during the Valsalva maneuver (n = 6) or palpable only in an erect position during the Valsalva maneuver (n = 2). Varicocele occurred on the left side in all 27 patients, although two patients had bilateral varicocele. Six patients had a history of surgical ligation of the varicocele. As a control group, 20 boys (age range, 7–17 years; mean, 11.4 years) without varicocele or hematuria underwent Doppler spectral analysis of the left renal vein (US was being performed for other clinical indications). There was no age difference between the two groups (P = .407 with the t test).

In all patients, who were all younger than 18 years, written informed consent was obtained from the parents. Informed consent was obtained from the parents of the control subjects, who were also younger than 18 years, for the performance of Doppler spectral analysis of the left renal vein. At the time our study began, institutional review board approval for our type of study was not a requirement at our university hospital, and the principles of the Declaration of Helsinki were followed. Since then, the requirement was established, and our study was reviewed by our institutional review board and was considered ethically sound, with proper human subject protection measures in place, including informed consent.

US Procedure
US was performed independently by two radiologists who had had 6 (W.S.K.) and 3 (J.E.C.) years of experience with pediatric Doppler US at the time our study started (in 1997). US of the left renal vein was performed with the patient in a supine position by using an HDI 3000 unit (Advanced Technology Laboratories, Bothell, Wash) equipped with a 2–4-MHz or a 4–7-MHz curved-array transducer. Anteroposterior diameter and peak velocity were measured in the transverse plane at two points in the left renal vein—one at the proximal portion of the left renal vein near the hilum in front of the lateral edge of the vertebral body, and the other where the left renal vein courses between the aorta and the superior mesenteric artery (aortomesenteric portion) (Fig 1a).


Figure 1
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  		Figure 1a: Doppler US images of the left renal vein. (a) Transverse image shows dilatation of proximal left renal vein (large arrows) and compression of left renal vein (small arrow) between the aorta (A) and superior mesenteric artery (S). (b, c) Doppler spectra obtained at transverse US at (b) hilar left renal vein and (c) aortomesenteric left renal vein show increased peak velocity at distal left renal vein between the aorta and superior mesenteric artery. Peak velocities were 17.5 cm/sec at the proximal left renal vein and 105.3 cm/sec at the distal left renal vein.

 

Figure 1
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  		Figure 1b: Doppler US images of the left renal vein. (a) Transverse image shows dilatation of proximal left renal vein (large arrows) and compression of left renal vein (small arrow) between the aorta (A) and superior mesenteric artery (S). (b, c) Doppler spectra obtained at transverse US at (b) hilar left renal vein and (c) aortomesenteric left renal vein show increased peak velocity at distal left renal vein between the aorta and superior mesenteric artery. Peak velocities were 17.5 cm/sec at the proximal left renal vein and 105.3 cm/sec at the distal left renal vein.

 

Figure 1
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  		Figure 1c: Doppler US images of the left renal vein. (a) Transverse image shows dilatation of proximal left renal vein (large arrows) and compression of left renal vein (small arrow) between the aorta (A) and superior mesenteric artery (S). (b, c) Doppler spectra obtained at transverse US at (b) hilar left renal vein and (c) aortomesenteric left renal vein show increased peak velocity at distal left renal vein between the aorta and superior mesenteric artery. Peak velocities were 17.5 cm/sec at the proximal left renal vein and 105.3 cm/sec at the distal left renal vein.

 
The Doppler angle was less than 60° in all cases, and wall filters were set at minimum. When Doppler spectra of the proximal left renal vein were obtained, a 2–4-mm sample volume was used; however, when Doppler spectra were obtained in the aortomesenteric portion, a sample volume of 4–10 mm was used to cover the range of movement of the left renal vein between the pulsating aorta and the superior mesenteric artery (Fig 1b). To minimize measured vessel diameter and velocity variations, each parameter was measured twice and the results were averaged. We calculated proximal-to-aortomesenteric left renal vein diameter ratios (diameter ratios) and aortomesenteric-to-proximal left renal vein peak velocity ratios (peak velocity ratios).

Venography
Thirteen of the 27 patients underwent left renal venography and renocaval pressure determinations during retrograde coil embolization of the varicocele. The clinical indications for varicocele embolization were as follows: testicular atrophy (n = 7), recurrence after surgical ligation (n = 6), and groin pain (n = 4). Venography was performed by a pediatric radiologist (W.S.K.) who had 7 years of experience with pediatric intervention. Venography was performed with local anesthesia of the patient to depict venous reflux, identify anatomic variations, and help evaluate the feasibility of varicocele transcatheter embolization. Left renal veins were catheterized by using an arched 5-F catheter with two side holes (Cobra visceral catheter; Cook, Melbourne, Australia) by means of the right femoral vein. Zero point pressures were adjusted at the level of the 11th rib, pull-back pressures were traced from the proximal left renal vein to the inferior vena cava, and pressure gradients between the left renal vein and the inferior vena cava were calculated.

The nutcracker phenomenon was diagnosed on the basis of left renal venographic findings, which included evidence of left renal vein compression between the aorta and the superior mesenteric artery, the presence of collateral veins, and, most important, a higher pressure in the left renal vein than in the inferior vena cava (renocaval pressure gradient [pressure in left renal vein minus pressure in inferior vena cava] ≥ 3 mm Hg) (8). The catheter was reintroduced into the left renal vein, and a venogram was obtained with the Valsalva maneuver. Venographic findings were categorized as renospermatic reflux with or without collateral veins; the ascending lumbar, adrenal, ureteral, and capsular veins are known to be potential collateral venous pathways in cases of left renal vein obstruction (5,8). Coil embolization was successful in 10 patients; technical failures occurred in three remaining patients.

Statistical Analysis
The one-sample Kolmogorov-Smirnov goodness-of-fit test was used to determine whether values were normally distributed. Absolute values and ratios of left renal vein diameter and peak velocity were compared between the two groups by using an independent-sample t test. We also evaluated the correlation between US parameters of the left renal vein and the pressure gradient measured by means of left renal venography by using the Pearson correlation coefficient. The Fisher exact test was used to investigate associations among the nutcracker phenomenon, the development of collateral veins, and varicocele clinical grade.

To determine the diagnostic performance of the left renal vein diameter ratio, the absolute peak velocity at the aortomesenteric portion of the left renal vein, and the peak velocity ratio of the left renal vein in the diagnosis of nutcracker phenomenon, receiver operating characteristic (ROC) analysis was performed. Ten patients with venographically confirmed nutcracker phenomenon and 23 participants without nutcracker phenomenon (20 healthy controls and three patients with negative findings for nutcracker phenomenon at venography [renocaval pressure gradient < 3 mm Hg]) were included in the ROC analysis. Areas under the ROC curves with 95% confidence intervals were calculated for the three US indexes. Cutoff values were determined by selecting the nearest coordinate on each ROC curve to the upper left corner (ie, 0,1) of the ROC graph. Values higher than the cutoff values indicated positivity for nutcracker phenomenon for each US index, which provided balance between sensitivity and specificity (ie, minimal false-negative and false-positive results). ROC analysis was performed with MedCalc 7.4 (MedCalc Software, Mariakerke, Belgium), which adopts the nonparametric method by Hanley and McNeil (14,15).

The sensitivities and specificities of each cutoff value were calculated for each US index, and differences in sensitivity values in the diagnosis of nutcracker phenomenon were tested for significance by performing the McNemar test. The other statistical analysis was performed with SPSS 11.5 for Windows (SPSS, Chicago, Ill). A two-tailed P value of less than .05 was considered to represent a significant difference.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 ADVANCE IN KNOWLEDGE
 References
 
Doppler US of the Left Renal Vein
In 27 patients with varicocele, the mean diameters (±standard deviation) of the proximal left renal vein and of the aortomesenteric portion of the left renal vein were 7.4 mm ± 1.7 (range, 5.0–13.3 mm) and 1.4 mm ± 0.4 (range, 0.8–2.4 mm), respectively. The corresponding mean diameters in the 20 control subjects were 5.7 mm ± 1.8 (range, 3.2–9.6 mm) and 1.7 mm ± 0.4 (range, 1.2–2.4 mm). The mean left renal vein diameter ratio was 5.7 ± 1.8 in patients with varicocele and 3.5 ± 1.0 in the control subjects. The diameters of the proximal left renal vein and the left renal vein diameter ratios were significantly different in the two groups (P < .001). In patients with varicocele, the peak flow velocities of the left renal vein were 21.8 cm/sec ± 5.5 (range, 10–35 cm/sec) in the proximal portion and 106.1 cm/sec ± 37.4 (range, 36–184 cm/sec) in the aortomesenteric portion. The corresponding mean peak flow velocities in the 20 control subjects were 19.0 cm/sec ± 3.0 (range, 13–25 cm/sec) and 58.7 cm/sec ± 16.8 (range, 39–88 cm/sec). The mean left renal vein peak velocity ratio was 5.2 ± 2.6 in patients with varicocele and 3.1 ± 0.8 in the control subjects. The peak flow velocities of the left renal vein in the aortomesenteric portion and the left renal vein peak velocity ratios were significantly different in the two groups (P < .005) (Table 1).


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  		Table 1. Doppler US Parameters of the Left Renal Vein in Patients with Varicocele and Control Subjects

 
Nutcracker Phenomenon
The renocaval pressure gradient between the left renal vein and the inferior vena cava (n = 13) ranged from 1 to 14 mm Hg (median, 4 mm Hg). The venographic criterion of the nutcracker phenomenon (renocaval pressure gradient ≥ 3 mm Hg) was met by 10 patients (77%). All 10 patients showed extrinsic compression of the left renal vein between the superior mesenteric artery and the aorta; they also had renospermatic reflux shown at venography. Multiple collateral venous channels were demonstrated by eight patients (Fig 2a, 2b). Among three patients with a low pressure gradient (<3 mm Hg), two showed renospermatic reflux without collateral venous channels and one showed mild renospermatic reflux only during the Valsalva maneuver (Fig 2c). With the Fisher exact test, an association was found between the presence of the nutcracker phenomenon and (a) varicocele grade (P = .038) and (b) the development of collateral veins (P = .035) (Table 2). A correlation was also found between this pressure gradient and peak flow velocity of the left renal vein in the hilar region (r = 0.607, P = .028), but no other Doppler US parameters were found to be significantly related with the pressure gradient.


Figure 2
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  		Figure 2a: Anteroposterior left renal venograms of three different patients with left varicocele. (a) View shows reflux of contrast material into dilated left internal spermatic vein (white arrows) and left adrenal vein (small black arrow). Compression of the left renal vein (large black arrow) is shown between the superior mesenteric artery and aorta. The pressure gradient between the left renal vein and inferior vena cava was 4 mm Hg. (b) View shows the left paravertebral venous plexus (arrows). The pressure gradient was 6 mm Hg. (c) View shows minimal renospermatic reflux (arrows). The pressure gradient was 1 mm Hg.

 

Figure 2
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  		Figure 2b: Anteroposterior left renal venograms of three different patients with left varicocele. (a) View shows reflux of contrast material into dilated left internal spermatic vein (white arrows) and left adrenal vein (small black arrow). Compression of the left renal vein (large black arrow) is shown between the superior mesenteric artery and aorta. The pressure gradient between the left renal vein and inferior vena cava was 4 mm Hg. (b) View shows the left paravertebral venous plexus (arrows). The pressure gradient was 6 mm Hg. (c) View shows minimal renospermatic reflux (arrows). The pressure gradient was 1 mm Hg.

 

Figure 2
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  		Figure 2c: Anteroposterior left renal venograms of three different patients with left varicocele. (a) View shows reflux of contrast material into dilated left internal spermatic vein (white arrows) and left adrenal vein (small black arrow). Compression of the left renal vein (large black arrow) is shown between the superior mesenteric artery and aorta. The pressure gradient between the left renal vein and inferior vena cava was 4 mm Hg. (b) View shows the left paravertebral venous plexus (arrows). The pressure gradient was 6 mm Hg. (c) View shows minimal renospermatic reflux (arrows). The pressure gradient was 1 mm Hg.

 

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  		Table 2. Association between Nutcracker Phenomenon, Varicocele Grade, and Collateral Vein Development

 
ROC Analysis
On the basis of these results, we set cutoff values for the left renal vein diameter ratios and peak velocity ratios and for the absolute value of the peak flow velocity at the aortomesenteric region for the diagnosis of the nutcracker phenomenon by means of ROC analysis. The area under the ROC curve was 0.854 (95% confidence interval: 0.688, 0.952) for diameter ratio, 0.824 (95% confidence interval: 0.652, 0.933) for peak velocity ratio, and 0.893 (95% confidence interval: 0.736, 0.973) for peak velocity at the aortomesenteric portion. The difference between area under the ROC curve values was not significant (P > .10). The calculated cutoff values were as follows: greater than 4.9 for the diameter ratio, greater than 4.9 for the peak velocity ratio, and greater than 80 cm/sec for the peak velocity in the aortomesenteric portion.

When these cutoff values were applied, the sensitivity of Doppler US was 80% (eight of 10) for diameter ratio, 90% (nine of 10) for peak velocity in the aortomesenteric portion, and 70% (seven of 10) for peak velocity ratio. The sensitivity of Doppler US was not significantly different among the three US cutoff values (P > .50). The specificity of Doppler US was 78% (18 of 23) for diameter ratio, 78% (18 of 23) for peak velocity in the aortomesenteric portion, and 96% (22 of 23) for peak velocity ratio. The specificity of Doppler US was not significantly different among the three US cutoff values (P > .50). According to these criteria, eight (80%) of 10 patients with varicocele and venographically confirmed nutcracker phenomenon had a dilated left renal vein (diameter ratio >4.9), seven patients (70%) had a high left renal vein peak velocity ratio (>4.9), and six patients (60%) had both (Table 3).


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  		Table 3. Left Renal Vein Doppler US Criteria of Varicocele: Comparison between Patients with Varicocele and Control Subjects

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
ADVANCE IN KNOWLEDGE
 References
 
Varicocele has been widely accepted as an important cause of male infertility and may be present in up to 20% of young men (1,2). Since varicocele of early adolescent onset was demonstrated to have a negative influence on testicular growth and function, efforts have focused on accurate diagnosis and effective treatment (16,17).

The nutcracker phenomenon has been implicated as a cause of varicocele by producing a persistent elevated renocaval pressure gradient and reflux down the internal spermatic vein and by promoting the development of collateral venous pathways (4–10). Mali et al (4) showed a good correlation between the renocaval pressure gradient and renospermatic reflux and found that the severity of left renal vein compression in the upright position determines the velocity of retrograde flow in the left spermatic vein and varicocele size. These findings correspond with our results. In our study, patients with the nutcracker phenomenon showed higher-grade varicocele and obvious collateral vein formation than did patients with a lower renocaval pressure gradient. However, in patients with a low renocaval pressure gradient, insufficiencies of the internal spermatic vein might be the main cause of renospermatic reflux (1–7).

Doppler US has been used to diagnose the nutcracker phenomenon in adults (10–13). Kim et al (10) identified Doppler US criteria related to the nutcracker phenomenon by measuring left renal vein diameter and peak flow velocity. They suggested that distal-to-proximal diameter ratios and flow velocity ratios exceeding 5.0 represented nutcracker phenomenon cutoff levels. In children, the use of Doppler US for the diagnosis of nutcracker phenomenon has been limited because the left renal vein sampling area is smaller and the Doppler angle is larger in children than in adults (18,19). Some authors have tried to measure the diameters of the left renal vein at its narrowest segment, as well as diameters proximal and distal to the narrowest segment, in order to determine the usefulness of US for the diagnosis of nutcracker phenomenon in children (18). Park et al (19) suggested Doppler US criteria for nutcracker phenomenon in children with orthostatic proteinuria: 3.98 for the peak velocity ratio and 4.16 for the anteroposterior diameter ratio. These authors reported that these Doppler US criteria might be used to screen patients suspected of having the nutcracker phenomenon. However, their study did not include left renal vein pressure measurements, which are considered the reference standard for the diagnosis of nutcracker phenomenon.

Takebayashi et al (12) reported that the detection of collateral veins around the left renal vein at color Doppler US is a reliable criterion for the diagnosis of nutcracker phenomenon. However, the left renal vein flow patterns and collateral vein formations associated with nutcracker phenomenon depend on the degree and stage of the phenomenon. In patients with early nutcracker phenomenon, left renal vein distention and high-pressure gradients exist before collateral veins develop. Moreover, in patients with collateral veins, the presence of a distended left renal vein and hypertension of the left renal vein indicate that the nutcracker phenomenon is noncompensatory. Multiple collateral veins with borderline left renal vein hypertension or without hypertension can suggest a compensatory state of the nutcracker phenomenon (12). We believe that most cases of varicocele in our study may have been in such a noncompensatory state.

To our knowledge, studies on the correlation between the Doppler parameters of the left renal vein and the renocaval pressure gradient in patients with varicocele have not yet been reported. Although Graif et al (13) found that a reduced flow velocity in the proximal left renal vein (induced by the pinching effect of the nutcracker phenomenon) in patients with varicocele and a greater reduction in left renal vein flow velocity were correlated with a smaller mesenteric angle, we found a positive correlation between the pressure gradient and peak velocity in the proximal left renal vein in patients with varicocele. We presume that a greater pinching effect results in a higher degree of reflux into the left internal spermatic vein and that the peak velocity in the proximal left renal vein might be increased by its "stealing" of left renal vein flow. Nevertheless, we believe that it is difficult to predict the renocaval pressure gradient on the basis of Doppler US–measured left renal vein flow velocities because the physiologic conditions in the left renal vein are complex. In nutcracker phenomenon, the left renal vein may supply or be supplied by gonadal, adrenal, or other collateral veins (2–4).

Our study had limitations. First, because the number of subjects was small, statistical errors are an issue. Second, we did not measure left renal vein pressure differences in the control group. Although relationships between left renal vein and inferior vena cava pressures have been studied in adults (7,8), to our knowledge normal left renal vein pressure values have not been reported in children. Third, only some of the children with varicocele underwent venography. Another limitation was that we examined the left renal vein in the supine position only. As reported in the literature, the nutcracker phenomenon may result from the compression of the left renal vein by the superior mesenteric artery in the upright position (20); therefore, we may have missed patients with varicocele who had the nutcracker phenomenon. Further study of the influence of patient position on Doppler US measurements with respect to the nutcracker phenomenon and postoperative follow-up of the left renal vein at Doppler US may provide useful information about hemodynamic changes in patients with varicocele.

In conclusion, the nutcracker phenomenon may be an important cause of pediatric varicocele. The high renocaval pressure gradient caused by the nutcracker phenomenon may provide the driving force for retrograde blood flow from the left renal vein into the internal spermatic vein in children with varicocele. Doppler spectral analysis and venography of the left renal vein can show hemodynamic changes in the left renal vein and help identify the presence of the nutcracker phenomenon in pediatric patients with varicocele.


   ADVANCE IN KNOWLEDGE
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCE IN KNOWLEDGE
References
 


   FOOTNOTES
 

Abbreviations: ROC = receiver operating characteristic

Authors stated no financial relationship to disclose.

Author contributions: Guarantors of integrity of entire study, W.S.K., J.E.C.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, W.S.K., J. E.C., S.H.K., K.M.Y.; clinical studies, W.S.K., J.E.C., I.O.K., K.M.K., H.C.; statistical analysis, J.E.C.; and manuscript editing, W.S.K., J.E.C., I.O.K., S.H.K., K.M.Y.


   References
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 ADVANCE IN KNOWLEDGE
 References
 

  1. Siegelman EV, Marmar JL. Pathophysiology, treatment, and imaging of male infertility. In: Pollack HM, McClennan BL, eds. Clinical urography. 2nd ed. Philadelphia, Pa: Saunders, 2000; 3017–3019.
  2. Fretz PC, Sandlow JI. Varicocele: current concepts in pathophysiology, diagnosis, and treatment. Urol Clin North Am 2002;29(4):921–937.[CrossRef][Medline]
  3. Zerhouni EA, Siegelman SS, Walsh PC, White RI. Elevated pressure in the left renal vein in patients with varicocele: preliminary observations. J Urol 1980;123(4):512–513.[Medline]
  4. Mali WP, Oei HY, Arndt JW, Kremer J, Coolsaet BL, Schuur K. Hemodynamics of the varicocele. II. Correlation among the results of renocaval pressure measurements, varicocele scintigraphy and phlebography. J Urol 1986;135(3):489–493.[Medline]
  5. Kim SH, Park JH, Han MC, Paick JS. Embolization of the internal spermatic vein in varicocele: significance of venous pressure. Cardiovasc Intervent Radiol 1992;15(2):102–106.[Medline]
  6. Carl P, Stark L, Ouzoun N, Reindl P. Venous pressure in idiopathic varicocele. Eur Urol 1993;24(2):214–220.[Medline]
  7. Braedel HU, Steffens J, Ziegler M, Polsky MS, Platt ML. A possible ontogenic etiology for idiopathic left varicocele. J Urol 1994;151(1):62–66.[Medline]
  8. Nishimura Y, Fushiki M, Yoshida M, et al. Left renal vein hypertension in patients with left renal bleeding of unknown origin. Radiology 1986;160(3):663–667.[Abstract/Free Full Text]
  9. Hohenfellner M, Steinbach F, Schultz-Lampel D, et al. The nutcracker syndrome: new aspects of pathophysiology, diagnosis and treatment. J Urol 1991;146(3):685–688.[Medline]
  10. Kim SH, Cho SW, Kim HD, Chung JW, Park JH, Han MH. Nutcracker syndrome: diagnosis with Doppler US. Radiology 1996;198(1):93–97.[Abstract/Free Full Text]
  11. Stavros AT, Sickler KJ, Menter RR. Color duplex sonography of the nutcracker syndrome (aortomesenteric left renal vein compression). J Ultrasound Med 1994;13:569–574.[Medline]
  12. Takebayashi S, Ueki T, Ikeda N, Fujikawa A. Diagnosis of the nutcracker syndrome with color Doppler sonography: correlation with flow patterns on retrograde left renal venography. AJR Am J Roentgenol 1999;172:39–43.[Abstract/Free Full Text]
  13. Graif M, Hauser R, Hirshebein A, Botchan A, Kessler A, Yabetz H. Varicocele and the testicular-renal venous route: hemodynamic Doppler sonographic investigation. J Ultrasound Med 2000;19(9):627–631.[Abstract]
  14. Hanley JA, McNeil BJ. The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology 1982;143:29–36.[Abstract/Free Full Text]
  15. Hanley JA, McNeil BJ. A method comparing the areas under receiver operator characteristic curves derived from the same cases. Radiology 1983;148:839–843.[Abstract/Free Full Text]
  16. Pallwein L, Pinggera G, Schuster AH, et al. The influence of left renal vein entrapment on outcome after surgical varicocele repair: a color Doppler sonographic demonstration. J Ultrasound Med 2004;23(5):595–601.[Abstract/Free Full Text]
  17. Richter F, Stock JA, LaSalle M, Sadeghi-Nejad H, Hanna MK. Management of prepubertal varicoceles: results of a questionnaire study among pediatric urologists and urologists with infertility training. Urology 2001;58(1):98–102.[CrossRef][Medline]
  18. Okada M, Tsuzuki K, Ito S. Diagnosis of the nutcracker phenomenon using two-dimensional ultrasonography. Clin Nephrol 1998;49:35–40.[Medline]
  19. Park SJ, Lim JW, Cho BS, Yoon TY, Oh JH. Nutcracker syndrome in children with orthostatic proteinuria: diagnosis on the basis of Doppler sonography. J Ultrasound Med 2002;21(1):39–45.[Abstract/Free Full Text]
  20. Sayfan J, Halevy A, Oland J, Nathan H. Varicocele and left renal vein compression. Fertil Steril 1984;41(3):411–417.[Medline]



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